Bicycles and scooters are common types of personal vehicles generally including a frame for carrying a person thereon and which is supported for rolling movement along the ground on a pair of wheels. Bicycles are typically manually propelled with a pedal and chain system whereas scooters typically provide a flat deck upon which the person stands for manually propelling the vehicle by pushing off the ground with one foot. In some instances however it is known to provide one wheel of the scooter supported for eccentric rotation whereby a jumping motion on the deck which is timed to match the oscillations of rotation of the eccentric wheel can give forward motion to the scooter. Known designs however do not readily permit conversion between concentric and eccentric rotation while in motion.
U.S. Pat. No. 3,371,944 to Daniels, U.S. Pat. No. 4,588,232 to Kim et al, U.S. Pat. No. 4,755,005 to Tsai, U.S. Pat. No. 6,186,918 to Yoo, U.S. Pat. No. 6,609,721 to Clift Jr. and U.S. Pat. No. 3,717,361 to Vanderpool disclose various examples of wheel assemblies which can be converted between eccentric and concentric modes of operation. In each instance however a single axle is provided which requires a complex arrangement of parts for actually moving the axle between the concentric mode in which the axle is concentric with the surrounding wheel and an eccentric mode in which the axle is radially offset from the centre of the wheel. In most examples the complex arrangement does not permit conversion while in motion whereas in other instances the complex configuration of the parts would likely be susceptible to jamming and would be difficult to maintain.